Diagnostic and Monitoring Value of 2D Shear Wave Elastography in Subacute Thyroiditis: A Prospective Case-Control Study.

PURPOSE: This study aimed to analyze the applicability of different shear wave elastography (SWE) methods in the diagnosis, differentiation, and monitoring of subacute thyroiditis (SAT). METHODS: This prospective study included 26 patients diagnosed with SAT and 40 healthy controls. All participants underwent conventional B-mode ultrasonography followed by two-dimensional shear wave elastography (2D-SWE), using a 4-15 MHz linear transducer (Aixplorer, Supersonic Imagine, France). Thyroid stiffness was assessed in kilopascals (kPa) and evaluated at diagnosis, 4 weeks, and 8 weeks. Statistical analysis included t-tests, repeated-measures ANOVA, receiver operating characteristic curve analysis, and Youden Index calculation to determine optimal diagnostic cut-off values. RESULTS: Baseline thyroid stiffness in SAT patients was significantly higher than in controls (127.25 ± 54.06 kPa vs. 19.5 ± 7.1 kPa; p < 0.001). Stiffness values decreased over time, reaching 117 ± 44.67 kPa at 4 weeks and 57.17 ± 22.89 kPa at 8 weeks. An exploratory cutoff value of 37.2 kPa showed complete separation between groups within this specific cohort. Beyond baseline group differences, the most relevant finding was the longitudinal change in thyroid stiffness during clinical recovery, supporting the role of SWE as a quantitative imaging biomarker of inflammatory activity. CONCLUSIONS: 2D-SWE showed promising performance as a quantitative imaging biomarker for evaluating and monitoring SAT in this exploratory cohort. It provides valuable quantitative data on tissue stiffness, complementing conventional ultrasound and aiding clinical decision-making during follow-up.